Internal threads can end up undersized because of the work material's properties or because of changes to the hole's dimensions caused by plating or heat-treating processes performed after tapping. This article explains H- and D-limits and how to use them to specify a tap that will produce the right size thread, regardless of any post-tapping operations.
Imported from the CTE archive to seed discussion on MFGAxis.
Originally published on CTE: 1996-08-01
CTE source: https://ctemag.com/articles/good-bad-and-retapped/
Legacy path: /articles/good-bad-and-retapped